@misc{KleinSchmidt, author = {Klein, Marten and Schmidt, Heiko}, title = {Investigating Schmidt number effects in turbulent electroconvection using one-dimensional turbulence}, series = {Proc. Appl. Math. Mech.}, volume = {21}, journal = {Proc. Appl. Math. Mech.}, publisher = {Wiley}, address = {Weinheim}, doi = {https://doi.org/10.1002/pamm.202100147}, pages = {1 -- 3}, abstract = {Turbulent electroconvection denotes a fluctuating multiphysical flow in which hydrodynamics and electrokinetics interact on multiple scales. The dynamical processes at work are entangled down to the molecular-diffusive scales that are determined by the Schmidt (Sc) and Reynolds (Re) number. Turbulence properties are generally nonuniversal which leads to high numerical resolution requirements. We address the numerical challenges associated with accuracy and feasibility by utilizing a stochastic one-dimensional turbulence (ODT) model. Here, ODT is applied to turbulent Couette flow of dilute electrolytes as canonical problem for turbulent electroconvection. For Sc ⩾ O(10), ODT predicts an increase of the skin friction drag due to electrohydrodynamically (EHD) enhanced small-scale eddy production once the flow is sufficiently turbulent.}, language = {en} } @misc{KleinMaierSchmidt, author = {Klein, Marten and Maier, Roland Erich and Schmidt, Heiko}, title = {Stochastic modeling of transient neutral and stably-stratified Ekman boundary layers}, series = {Special Issue: 92nd Annual Meeting of the International Association of Applied Mathematics and Mechanics (GAMM)}, volume = {21}, journal = {Special Issue: 92nd Annual Meeting of the International Association of Applied Mathematics and Mechanics (GAMM)}, publisher = {Wiley}, address = {Weinheim}, doi = {10.1002/pamm.202100146}, pages = {1 -- 3}, abstract = {Neutral and stably-stratified Ekman boundary layers (EBLs) are numerically investigated with a stochastic one-dimensional turbulence (ODT) model. EBLs achieve the bulk-surface coupling in Earth's atmosphere. They are numerically challenging due to transient and non-universal turbulence properties even at small scales. ODT addresses this problem by distinguishing turbulent-advective from molecular-diffusive transport processes for a vertical column along which all relevant scales of the flow are resolved. We demonstrate the model's capabilities for economical, accurate, and stratification regime independent simulation of EBLs for the wind-turning angle. ODT reproduces and extrapolates reference direct numerical simulation results consistent with observations. We conclude that ODT may be useful for modeling of atmospheric surface layers.}, language = {en} } @misc{MedinaMendezSchmidt, author = {Medina M{\´e}ndez, Juan Ali and Schmidt, Heiko}, title = {Towards the application of the One-Dimensional Turbulence model for the evaluation of collection efficiencies in wire-tube electrostatic precipitators}, series = {Proceedings in Applied Mathematics and Mechanics}, volume = {21}, journal = {Proceedings in Applied Mathematics and Mechanics}, number = {1}, issn = {1617-7061}, doi = {10.1002/pamm.202100220}, pages = {3}, language = {en} } @misc{MedinaMendezFreireSchmidt, author = {Medina M{\´e}ndez, Juan Ali and Freire, Livia S. and Schmidt, Heiko}, title = {One-Dimensional Turbulence in channels with rough walls}, series = {Jahresbericht 2021 zum 20. STAB-Workshop 16.-17. November 2021 G{\"o}ttingen}, volume = {2021}, journal = {Jahresbericht 2021 zum 20. STAB-Workshop 16.-17. November 2021 G{\"o}ttingen}, publisher = {Deutsche Str{\"o}mungsmechanische Arbeitsgemeinschaft, STAB}, address = {G{\"o}ttingen}, pages = {108 -- 109}, language = {en} } @misc{StarickSchmidt, author = {Starick, Tommy and Schmidt, Heiko}, title = {Stochastische Modellierung einer Methan/Luft Freistrahl-Flamme mit detaillierter Chemie}, series = {30. Deutscher Flammentag, Hannover-Garbsen, 28-29 September 2021}, journal = {30. Deutscher Flammentag, Hannover-Garbsen, 28-29 September 2021}, pages = {10}, abstract = {Die vorliegende Arbeit befasst sich mit der stochastischen Modellierung einer Methan/Luft Freistrahl-Flamme unter Verwendung des One-Dimensional Turbulence (ODT) Modells. Bei der untersuchten Cabra-Brennerkonfiguration handelt es sich um ein offenes System, bei welchem ein vorgemischter Methan/Luft Freistrahl von einer zentral angeordneten D{\"u}se in eine Umgebungsstr{\"o}mung aus heißen Verbrennungsgasen str{\"o}mt. Das One-Dimensional Turbulence Modell ist ein stochastisches und abbildungsbasiertes Modell, welches die molekulare Diffusion und Reaktionskinetik durch sich zeitlich entwickelnde, deterministische Erhaltungsgleichungen ber{\"u}cksichtigt und entlang eines eindimensionalen Rechengebietes vollst{\"a}ndig aufl{\"o}st. Die Besonderheit von ODT liegt in der Modellierung der turbulenten Advektion {\"u}ber zuf{\"a}llig auftretende Wirbelereignisse, welche den fundamentalen Erhaltungseigenschaften unterliegen. F{\"u}r die Abbildung der Methan/Luft Verbrennungschemie wird ein reduzierter Mechanismus mit 19 Spezies und 15 Reaktionen und ein detaillierter Mechanismus mit 53 Spezies und 325 Reaktionen eingesetzt. Die gezeigten vorl{\"a}ufigen ODT-Simulationsergebnisse der Methan/Luft Freistrahl-Flamme beinhalten Mittellinienprofile, radiale Profile, Streudiagramme und zweidimensionale Visualisierungen der Freistrahl-Flamme, welche mit einer zylindrischen Formulierung von ODT erzeugt wurden. Zu Vergleichszwecken werden die Simulationsergebnisse experimentellen Messungen gegen{\"u}bergestellt. Obwohl die Simulation von reaktiven Freistrahl-Flammen keinen neuen Anwendungsfall von ODT darstellt, ist die akkurate Wiedergabe des sensiblen Zusammenspiels des zun{\"a}chst unverbrannten Freistrahls mit der heißen Umgebungsstr{\"o}mung eine Herausforderung f{\"u}r das Modell. In der durchgef{\"u}hrten Studie konnte gezeigt werden, dass die mittels ODT erzeugten Statistiken eine beachtlich gute {\"U}bereinstimmung mit den Vergleichsdaten aufweisen. Im Hinblick auf die reduzierte Dimensionalit{\"a}t von ODT, die Qualit{\"a}t der erzielten Ergebnisse und die erforderliche Rechenleistung, stellt ODT ein attraktives Modell zur Simulation von turbulenten und reaktiven Str{\"o}mungen dar.}, language = {de} } @misc{KleinFreireLignelletal., author = {Klein, Marten and Freire, Livia S. and Lignell, David O. and Kerstein, Alan R. and Schmidt, Heiko}, title = {Ein stochastischer Ansatz zur Modellierung fluktuierender Oberfl{\"a}chenfl{\"u}sse in turbulenten Grenzschichten}, series = {Kurzfassungen der Meteorologentagung DACH}, volume = {2022}, journal = {Kurzfassungen der Meteorologentagung DACH}, publisher = {Copernicus}, doi = {10.5194/dach2022-22}, pages = {1 -- 1}, abstract = {Im Konferenzbeitrag wird auf die Formulierung des stochastischen Modells eingegangen und gezeigt, dass neben Scherspannungen auch Druck-, Coriolis- und Auftriebskr{\"a}fte ber{\"u}cksichtigt werden k{\"o}nnen. Das Modell wird beispielhaft als unabh{\"a}ngiges, numerisches Werkzeug angewendet, um fluktuierende Oberfl{\"a}chenfl{\"u}sse in turbulenten Kanalstr{\"o}mungen sowie stabilen und konvektiven Grenzschichten zu untersuchen. Es werden sowohl glatte, als auch raue bzw. bewachsene (por{\"o}se) Oberfl{\"a}chen betrachtet. Anhand neuer Ergebnisse wird demonstriert, dass der Modellansatz in der Lage ist, Referenzdaten zufriedenstellend zu reproduzieren und extrapolieren. Daneben werden aktuelle Arbeiten zur Kopplung des stochastischen Modellansatzes mit Large-Eddy-Simulationen vorgestellt. Es wird gezeigt, dass die stochastische Modellierung oberfl{\"a}chennaher, subgitterskaliger Schwankungen in der Lage ist, wandnahe Turbulenzspektren zu reproduzieren und den filterbasierten Modellfehler bei ansonsten fester Gitteraufl{\"o}sung zu verringern.}, language = {de} } @misc{KersteinLignellSchmidtetal., author = {Kerstein, Alan R. and Lignell, David O. and Schmidt, Heiko and Starick, Tommy and Wheeler, Isaac and Behrang, Masoomeh}, title = {Using Hips As a New Mixing Model to Study Differential Diffusion of Scalar Mixing in Turbulent Flows}, series = {2021 AIChE Annual Meeting}, journal = {2021 AIChE Annual Meeting}, abstract = {Mixing two or more streams is ubiquitous in chemical processes and industries involving turbulent liquid or gaseous flows. Modeling turbulent mixing flows is complicated due to a wide range of time and length scales, and non-linear processes, especially when reaction is involved. On the other hand, in turbulent reacting flows, sub-grid scales need to be resolved accurately because they involve reactive and diffusive transport processes. Transported PDF methods use mixing models to capture the interaction in the sub-grid scales. Several models have been used with varying success. In this study, we present a novel model for simulation of turbulent mixing called Hierarchical Parcel Swapping (HiPS). The HiPS model is a stochastic mixing model that resolves a full range of time and length scales with the reduction in the complexity of modeling turbulent reacting flows. This model can be used as a sub-grid mixing model in PDF transport methods, as well as a standalone model. HiPS can be applied to transported scalars with variable Schmidt numbers to capture the effect of differential diffusion which is important for modeling scalars with low diffusivity like soot. We present an overview of the HiPS model, its formulation for variable Schmidt number flows, and then present results for evaluating the turbulence properties including the scalar energy spectra, the scalar dissipation rate, and Richardson dispersion. These model developments are an important step in applying HiPS to more complex flow configurations.}, language = {en} } @misc{StarickLignellSchmidt, author = {Starick, Tommy and Lignell, David O. and Schmidt, Heiko}, title = {Stochastic Modeling of a Lifted Methane/Air Jet Flame with Detailed Chemistry}, series = {Proceedings in Applied Mathematics \& Mechanics}, volume = {20}, journal = {Proceedings in Applied Mathematics \& Mechanics}, number = {1}, issn = {1617-7061}, doi = {10.1002/pamm.202000316}, pages = {3}, abstract = {This preliminary numerical study investigates a lifted methane/air jet flame in a vitiated coflow by means of the One-Dimensional Turbulence (ODT) model. In the considered Cabra Burner configuration [Combust. Flame 143 491-506 (2005)], a jet flame issues from a central nozzle into a vitiated coflow of hot combustion products from lean premixed hydrogen/air flames. ODT is a map-based model for turbulent flow simulations which uses a stochastic formulation for the turbulent advection. The diffusion and reaction effects along the one-dimensional domain are considered by temporally advancing deterministic evolution equations. ODT simulations are performed with a representation of the methane/air chemistry by a detailed 53-species mechanism with 325 reactions. In this work, we present centerline profile of temperature and species concentrations obtained from ODT simulations using a cylindrical ODT-formulation. Additionally, a two-dimensional rendering of the temperature distribution is shown. Although the simulation of reactive jet configurations by means of ODT is not novel, the complex stabilization region depending on the flow conditions represents a challenge for the model. Considering the reduced order of the model, ODT is able to predict the flow characteristics and reasonably matches the existing experimental data.}, language = {en} } @misc{StarickLignellSchmidt, author = {Starick, Tommy and Lignell, David O. and Schmidt, Heiko}, title = {Stochastic Modeling of a Lifted Methane/Air Jet Flame with Detailed Chemistry}, series = {91th Annual Meeting of the International Association of Applied Mathematics and Mechanics March 15-19, 2021 Kassel, DE}, journal = {91th Annual Meeting of the International Association of Applied Mathematics and Mechanics March 15-19, 2021 Kassel, DE}, doi = {10.1002/pamm.202100237}, pages = {3}, language = {en} } @misc{XieStarickMosgowetal., author = {Xie, Tianxiao and Starick, Tommy and Mosgow, Anatol and Berg, Heinz Peter and H{\"o}schler, Klaus and Schmidt, Heiko}, title = {Thermofluiddynamic pre-design of a primary surface heat exchanger under the influence of heat radiation using 1D/3D coupled simulation method}, series = {NAFEMS World Congress 2021, online, 25-29. Oktober 2021}, journal = {NAFEMS World Congress 2021, online, 25-29. Oktober 2021}, pages = {25}, abstract = {Within the Framework of the "TurboFuelCell (TFC)" a highly integrated and compact energy conversion system based on Micro Gas Turbine Solid Oxide Fuel Cell (MGT-SOFC) hybrid process is being developed by the team at BTU-Cottbus Senftenberg. This work focuses on the extension of the pre-design process of a primary surface heat exchanger (PSHX), which is a key component for the coupling between MGT and SOFC, using an 1D/3D hybrid simulation method for the understanding of its behaviour under the influence of heat radiation. In a MGT-SOFC hybrid process the high temperature heat exchanger plays an important role in preheating the fresh air to a minimum operation temperature necessary for SOFC. Due to the special location of this PSHX in the TFC, it is constantly exposed to heat radiation from the SOFC module, which requires additional consideration of its influence for better model accuracy. A first design, which is later extended through an 1D Flow network model, based on 𝜖 - 𝑁𝑇𝑈 method is presented. A complete 3D-CFD simulation with consideration of heat radiation is initially employed for the whole flow process to examine the first design. However, this approach proves to be highly computationally expensive due to the large dimensional difference between the plenum for cathode exhaust air and the fine channels in the PSHX. To reduce the computational effort, the flow and heat transfer in the PSHX is modelled by 1D elements. The flow in the plenum is simulated by 3D-CFD, which better accounts for convection and thermal radiation. A comparison between 3D-CFD and 1D/3D hybrid model is performed. A significant reduction of simulation time and computing resources can be achieved for well calibrated hybrid model without compromising on accuracy. In the talk, the effect of insulation layer thickness variations on the heat transfer on the plenum side due to heat radiation and their influence on the heat exchanger efficiency are discussed. Consequently, design improvements are realized based on the previous findings. Finally, the 1D/3D hybrid simulation method is evaluated and prepared for the general applications in thermal management of machines based on coupled MGT-SOFC process.}, language = {en} } @misc{SharmaKleinSchmidt, author = {Sharma, Sparsh and Klein, Marten and Schmidt, Heiko}, title = {Modelling turbulent jets at high-Reynolds number using one-dimensional turbulence}, series = {AIAA AVIATION 2021 FORUM}, journal = {AIAA AVIATION 2021 FORUM}, publisher = {American Institute of Aeronautics and Astronautics, Inc.}, isbn = {978-1-62410-610-1}, doi = {10.2514/6.2021-2104}, language = {en} } @misc{SharmaKleinSchmidt, author = {Sharma, Sparsh and Klein, Marten and Schmidt, Heiko}, title = {Features of far-downstream asymptotic velocity fluctuations in a round jet: A one-dimensional turbulence study}, series = {Physics of Fluids}, volume = {34}, journal = {Physics of Fluids}, number = {8}, issn = {1089-7666}, doi = {10.1063/5.0101270}, language = {en} } @misc{KleinSchmidt, author = {Klein, Marten and Schmidt, Heiko}, title = {Stochastic modeling of transient Ekman flow at arbitrary Reynolds number driven by horizontal bottom wall oscillation}, series = {EMS Annual Meeting 2022, Abstracts}, volume = {19}, journal = {EMS Annual Meeting 2022, Abstracts}, publisher = {Copernicus}, address = {Bonn, Germany}, doi = {10.5194/ems2022-617}, language = {en} } @misc{TsaiSchmidtKlein, author = {Tsai, Pei-Yun and Schmidt, Heiko and Klein, Marten}, title = {Modeling simultaneous momentum and passive scalar transfer in turbulent annular Poiseuille flow}, series = {92nd Annual Meeting of GAMM}, journal = {92nd Annual Meeting of GAMM}, publisher = {Gesellschaft f{\"u}r angewandte Mathematik und Mechanik e.V.}, address = {Aachen, Germany}, language = {en} } @misc{KleinTsaiSchmidt, author = {Klein, Marten and Tsai, Pei-Yun and Schmidt, Heiko}, title = {Stochastic modeling of heat and momentum transfer in annular pipe flow: A one-dimensional turbulence study with comparison to DNS and LES}, series = {STAB Jahresbericht 2022}, volume = {23}, journal = {STAB Jahresbericht 2022}, publisher = {Deutsche Str{\"o}mungsmechanische Arbeitsgemeinschaft (STAB)}, address = {G{\"o}ttingen, Germany}, language = {en} } @misc{KleinMedinaMendezSchmidt, author = {Klein, Marten and Medina M{\´e}ndez, Juan Al{\´i} and Schmidt, Heiko}, title = {Modeling electrohydrodynamically enhanced drag in channel and pipe flows using one-dimensional turbulence}, series = {Conference on Modelling Fluid Flow (CMFF'22)}, journal = {Conference on Modelling Fluid Flow (CMFF'22)}, address = {Budapest, Hungary}, pages = {1 -- 8}, language = {en} } @misc{KleinMedinaMendezSchmidt, author = {Klein, Marten and Medina M{\´e}ndez, Juan Al{\´i} and Schmidt, Heiko}, title = {Modeling electrohydrodynamically enhanced drag in channel and pipe flows using One-Dimensional Turbulenc}, series = {Proceedings of the Conference on Modelling Fluid Flow (CMFF'22)}, journal = {Proceedings of the Conference on Modelling Fluid Flow (CMFF'22)}, editor = {Vad, Janos}, publisher = {University of Technology and Economics, Department of Fluid Mechanics}, address = {Budapest, Hungary}, isbn = {978-963-421-881-4}, pages = {82 -- 91}, abstract = {The joint modeling of flow hydrodynamics and electrokinetics is a relatively unexplored area of turbulent flow research. We address a lack of available models for electrohydrodynamic (EHD) turbulent flow utilizing a lower-order approach, the stochastic One-Dimensional Turbulence (ODT) model. ODT is constructed on the principles of the direct energy cascade of Navier-Stokes turbulence, with key emphasis on the accurate resolution of the small molecular transport scales within a notional line-of-sight. We investigate two canonical flow configurations to demonstrate the applicability of the model in the simulation of EHD flows. First, we investigate EHD effects in zero-pressure-gradient turbulent boundary layers by two-way coupled model application to plane Couette flow of a dilute electrolyte. Second, we apply the one-way coupled model to EHD-enhanced gas flow through a vertical pipe with an inner concentric electrode, where electric fields are generated by means of a corona discharge and the corresponding effect of a continuum ionic charge density field.}, language = {en} } @misc{KleinZenkerStaricketal., author = {Klein, Marten and Zenker, Christian and Starick, Tommy and Schmidt, Heiko}, title = {Stochastic modeling of three-scalar mixing in a coaxial jet using one-dimensional turbulence}, series = {12th International Symposium on Turbulence and Shear Flow Phenomena (TSFP12), Osaka, Japan (Online), July 19-22, 2022}, journal = {12th International Symposium on Turbulence and Shear Flow Phenomena (TSFP12), Osaka, Japan (Online), July 19-22, 2022}, pages = {1 -- 6}, abstract = {Modeling complex mixing processes is a standing challenge for a number of applications ranging from chemical to mechanical and environmental engineering. Here, the gas-phase turbulent mixing in a three-stream concentric coaxial jet is investigated as a canonical problem. Reynolds-averaged Navier-Stokes simulations (RANS) suggest that the gas-phase mixing can be accurately modeled by air doped with passive scalars, for which small-scale resolving numerical simulations are performed with the one-dimensional turbulence (ODT) model as stand-alone tool. We show that both the spatial (S-ODT) and temporal (T-ODT) model formulations yield qualitatively similar results exhibiting reasonable to good agreement with available reference experiments, Reynolds-averaged and large-eddy simulations, as well as mixing models. This is demonstrated for low-order statistics, like the scalar variance and dissipation, but also the two-scalar joint probability density functions that can not be obtained with RANS. Our results suggest that S-ODT has better capabilities than T-ODT to model the mixing processes in the jet which we attribute to the account of local advective time scales.}, language = {en} } @misc{MedinaMendezSchmidtForooghietal., author = {Medina M{\´e}ndez, Juan Ali and Schmidt, Heiko and Forooghi, Pourya and Freire, Livia S.}, title = {Parametric forcing for roughness in turbulent channel flows: reduced order modelling using One-Dimensional Turbulence}, series = {EFMC14, 14th European Fluid Mechanics Conference, Athens, Greece, 13-16 September 2022, Book of Abstracts}, journal = {EFMC14, 14th European Fluid Mechanics Conference, Athens, Greece, 13-16 September 2022, Book of Abstracts}, pages = {S. 67}, language = {en} } @misc{MedinaMendezBacherSchmidtetal., author = {Medina M{\´e}ndez, Juan Ali and Bacher, Christian and Schmidt, Heiko and Riebel, Ulrich}, title = {A dusty gas approach for electrostatic precipitation of monodisperse aerosols using One-Dimensional Turbulence}, series = {4th International Symposium on Multiscale Multiphase Process Engineering (MMPE) 2022, Berlin, Germany, 25-28 September 2022, Book of Abstracts}, journal = {4th International Symposium on Multiscale Multiphase Process Engineering (MMPE) 2022, Berlin, Germany, 25-28 September 2022, Book of Abstracts}, language = {en} }